Polyvinyl chloride compositions plasticized with copolyesters

ABSTRACT

Copolyester plasticizers useful for the formulation of PVC refrigerator gaskets which exhibit improved resistance to migration and marring and improved processing characteristics are provided. The copolyesters are obtained by reacting an acid component consisting of a mixture of a benzene dicarboxylic acid (or anhydride or methyl ester thereof) and an aliphatic C 5-12  saturated dicarboxylic acid (or methyl ester) with an alcohol component consisting of a mixture of neopentyl glycol and ethylene glycol. An aliphatic C 6-13  saturated monofunctional alcohol or aliphatic C 6-13  saturated monocarboxylic acid terminating agent is also included in the reaction.

CROSS REFERENCE TO RELATED APPLICATION

This is a division of copending patent application Ser. No. 041,503,filed Apr. 23, 1987 now U.S. Pat. No. 4,824,990 which is acontinuation-in-part of application Ser. No. 863,634, filed May 15,1986, abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to improved copolyester plasticizercompositions useful for the formulation of PVC refrigerator gasketswhich exhibit good resistance to migration and marring and improvedprocessing characteristics.

2. Description of the Prior Art

For a compound is to be an effective plasticizer for PVC and impart thedesired softening, flexibilizing and toughening, the material must havesome mobility within the PVC resin. If this mobility is not properlycontrolled, however, the plasticizer can migrate into other resins withwhich the plasticized PVC comes in contact.

Migration of PVC plasticizers into high impact polystyrene andacrylonitrile-butadiene-styrene (ABS) resins is a particular problem.Many of the ester compounds commonly used for the plasticization of PVCmar the surface of the polystyrene or ABS in those regions where theresins come into contact with the plasticized PVC. In severe cases,stress cracking of the polystyrene and ABS resulting in rapid andcatastrophic failure of the resin can occur.

Various polyester compositions have been developed to overcome theabove-described problems. These polyesters are typically derived frombranched-chain diols and aliphatic dicarboxylic acids. Viscosities arecontrolled by the use of conventional monocarboxylic acid ormonofunctional alcohol terminators. Whereas acceptable migrationcharacteristics can be achieved with these polyesters, the plasticizersare more expensive than polyesters based on phthalates and ethyleneglycol. Copolyesters containing phthalates and copolyesters wherein allor a portion of the propylene glycol is replaced with ethylene glycolhave heretofore been found to have unacceptable mar characteristics.

Williams et al., U.S. Pat. No. 3,972,962 discloses chain-terminatednon-migrating polyester plasticizers for PVC derived from aliphaticsaturated dicarboxylic acids and branched-chain glycols. An aromaticmonocarboxylic acid is necessarily employed as a chain terminator toobtain the desired balance of plasticizer properties.

Aylesworth et al. in U.S. Pat. Nos. 3,501,554 and 3,595,824 disclosenon-chain terminated polyester plasticizers for PVC fabrics obtained bythe reaction of two or more alkanedioic acids having from 4 to 12 carbonatoms with two or more alkylene glycols having from 2 to 6 carbon atoms.The Aylesworth et al. plasticizer compositions exhibit superiorresistance to drycleaning solvents, such as perchloroethylene.

Lamont et al. U.S. Pat. No. 4,122,057 discloses polyesters which areterminated with a mixture of an aliphatic monobasic acid and amonofunctional alcohol. As a result of this mixed-termination,plasticizers having improved low temperature properties are obtained.

Copolyester plasticizers and a process for their production are alsodescribed in Uno et al., U.S. Pat. No. 4,065,439. The copolyesters ofUno et al. are derived from terephthalic acid, isophthalic acid, a C₆₋₉aliphatic dicarboxylic acid, ethylene glycol, and neopentyl glycol.These copolyesters are solid materials primarily useful as hot-melt typeadhesives, however, they may also be used for paints, surface treatingagents, binders and plasticizers.

U.S. Pat. No. 3,700,957 to Daniels discloses polyester compositionshaving both flame retarding and plasticizing properties obtained by thereaction of a dicarboxylic acid, a glycol and2,3-dibromomethyl-1,3-propanediol. The polyesters may be terminated withan alkanoic acid or alkanol chain terminator.

Other polyester plasticizers derived from diols and dicarboxylic acidsare disclosed in Small et al., U.S. Pat. No. 2,555,062; Wilkinson etal., U.S. Pat. No. 2,815,354; and Walus, U.S. Pat. No. 3,850,871.

It would be highly advantageous if non-migrating polyester plasticizerssuitable for use in PVC resins and which exhibit good plasticizationefficiency so that they can be utilized at low levels could be producedfrom low cost and readily available reactants. It would be even moredesirable if these plasticizers impart desirable processingcharacteristics to the PVC resin and exhibited reduced tendency to marpolystyrene and ABS resins. These and other advantages are realized withthe improved copolyester plasticizers of the present invention.

SUMMARY OF THE INVENTION

The improved copolyester plasticizer compositions of the presentinvention have average molecular weights from about 500 to 2000,kinematic viscosities (100° F.) from about 600 to about 2000 centistokesand are obtained by reacting a mixture containing a benzene dicarboxylicacid or anhydride or methyl ester thereof and an aliphatic saturateddicarboxylic acid having from 5 to 12 and, more preferably, 5 to 9carbon atoms or methyl ester thereof with a mixture of neopentyl glycoland ethylene glycol, and a terminating agent. The terminating agent canbe an aliphatic saturated monofunctional alcohol having from 6 to 13carbon atoms or an aliphatic saturated monocarboxylic acid having fromabout 6 to 13 carbon atoms or mixtures thereof.

To obtain the copolyesters essentially stoichiometric amounts of acidand alcohol components are reacted to an acid value less than about 3and hydroxyl value less than about 25. To aid in driving the reactionessentially to completion, a slight excess of ethylene glycol and/ormonofunctional alcohol may be employed. About 40 to 60 equivalentpercent aliphatic saturated dicarboxylic acid and 40 to 60 equivalentpercent benzene dicarboxylic acid, based on the total acid equivalents,are reacted. Ethylene glycol is generally reacted in an amount fromabout 30 to about 60 equivalent percent and neopentyl glycol is reactedin an amount from about 30 to 60 equivalent percent, based on the totalalcohol equivalents. About 8 to 30 equivalent percent monofunctionalalcohol, based on the total alcohol equivalents, or about 8 to 30equivalent percent monocarboxylic acid, based on the total acidequivalents, is generally reacted. The copolyesters are advantageouslyutilized to plasticize PVC homopolymer and copolymer resins and aregenerally employed in amounts ranging from 30 to about 150 phr.

DETAILED DESCRIPTION OF THE INVENTION

The improved copolyester plasticizers of the present invention are thereaction product of essentially stoichiometric amounts of a mixed acidcomponent and a mixed alcohol component. As used herein, the acidcomponent includes anhydrides or methyl esters. The acid mixturecontains one or more aliphatic saturated dicarboxylic acids and abenzene dicarboxylic acid. The alcohol component is a mixture ofethylene glycol and neopentyl glycol. An aliphatic monofunctionalalcohol or aliphatic monocarboxylic acid is used as a chain terminator.It will be understood that anhydrides and methyl esters may besubstituted for the various carboxylic acids and, in some instances,will be advantageous.

Aliphatic saturated dicarboxylic acids utilized for the preparation ofcopolyesters contain from 5 to 12 carbon atoms. Representativedicarboxylic acids include glutaric acid, adipic acid, pimelic acid,suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, andmixtures thereof. Other aliphatic dicarboxylic acids outside thespecified carbon content range may be present in limited quantities.Methyl esters of the aliphatic dicarboxylic acids may be advantageouslyutilized. Highly efficient plasticizer compositions are obtained whenglutaric acid, adipic acid, azelaic acid or mixtures wherein these acidsare the predominant acids are employed for the preparation of thecopolyesters.

In a particularly useful embodiment of this invention, methyl esters ofmixed dicarboxylic acids wherein the predominant dicarboxylic acids areglutaric acid and adipic acid and which are obtained as a co-productstream from the production of adipic acid are utilized. The ratio ofdimethyl glutarate to dimethyl adipate in these mixtures typicallyranges from 4:1 to 1:1 and, most generally, is from 3.5:1 to 2:1.

A benzene dicarboxylic acid is utilized in conjunction with theabove-described aliphatic dicarboxylic acids or methyl esters. Thebenzene dicarboxylic can be the ortho-, meta-, or para-isomer, i.e.,phthalic acid, isophthalic acid, or terephthalic acid. The ortho andpara derivatives are generally preferred. As with the aliphaticdicarboxylic acids, methyl esters of the benzene dicarboxylic acids mayalso be used. It will be also understood by those skilled in the artthat the anhydride of phthalic acid can also be utilized for thepreparation of the copolyester products. In a particularly usefulembodiment of the invention wherein copolyesters having superiorresistance to marring are obtained, dimethyl terephthalate is employed.

A hydroxylic component is reacted with the above-described mixture ofacids to obtain the useful copolyester plasticizers of this invention.This alcohol component contains ethylene glycol and neopentyl glycol,present in a prescribed ratio.

A monofunctional alcohol or monocarboxylic acid is also necessarilypresent as a chain-stopper, i.e., terminator. Branched-chain or linearaliphatic saturated monofunctional alcohols or monocarboxylic acidshaving from 6 to 13 carbon atoms and, more preferably, 8 to 10 carbonatoms are utilized for this purpose. Representative monofunctionalalcohols include 2-ethylhexanol, isooctyl alcohol, isodecyl alcohol,tridecyl alcohol, n-hexanol, n-octanol, n-decanol, and the like ormixtures thereof. Representative monocarboxylic acid terminators include2-ethylhexanoic acid, octanoic acid, pelargonic acid, isoheptanoic aciddecanoic acid, and the like or mixtures thereof. Mixtures of alcohol andacid terminators may also be advanntageously used.

Although the individual reactants employed to obtain the improvedplasticizers of this invention are known for the preparation ofpolyesters, the present copolyester compositions are novel as a resultof the particular combination of these reactants and the unique andunexpected properties obtained thereby. Whereas the skilled artisanwould expect migration and resistance to marring to be unacceptable as aresult of the introduction of an aromatic acid and substitution ofethylene glycol for a portion of the neopentyl glycol, this is not thecase. Applicants have quite unexpectedly found that both aromatic acidsand ethylene glycol can be advantageously utilized to reduce the cost ofthe product while obtaining acceptable migration properties. This isaccomplished by judicious selection of the dicarboxylic acids,hydroxylic compounds, and the ratio of these reactants. The superiormigration properties and resistance to marring obtained with the presentcopolyester products are even more more unexpected in view of therelatively low molecular weight of these products. Also, the improvedprocessing characteristics of PVC plasticized with the resultingcopolyesters is totally unexpected.

To obtain the improved copolyester plasticizers essentiallystoichiometric amounts of the acid component and the alcohol componentare reacted. The aliphatic saturated dicarboxylic acid comprises fromabout 40 to about 60 equivalent percent of the total acid equivalentsand the benzene dicarboxylic acid constitutes from about 40 to about 60equivalent percent of the total acid equivalents. The ethylene glycol ispresent in an amount from about 30 to about 60 equivalent percent, basedon the total equivalents of alcohol in the mixture. Neopentyl glycol ispresent in an amount from about 30 to about 60 equivalent percent, basedon the total alcohol equivalents. The aliphatic saturated monofunctionalalcohol or monocarboxylic acid terminator is employed in an amount fromabout 8 to about 30 equivalent percent, based on the total equivalentsof alcohol or acid.

The resulting copolyesters generally have average molecular weights inthe range 500 to about 2000. Most usually, the average molecular weightranges from 700 to about 1400. Molecular weights referred to herein arenumber average molecular weights determined by gel permeation utilizingconventional standards. The copolyesters have 100° F. kinematicviscosities in the range 600 to about 2000 centistokes and, moregenerally, in the range 900 to 1300 centistokes. The acid value of theproducts is generally 3 or less and the hydroxyl value is generally 25or less.

The copolyesters are prepared using known esterification andtransesterification techniques. Reaction of the acid and alcoholcomponents to obtain the desired copolyesters is carried out in standardequipment using conventional procedures. Typically, all of the reactantsare charged to a suitable kettle and heated at atmospheric pressure attemperatures on the order of about 150°-250° C. for a period of timesufficient to substantially complete the reaction. A catalyst may beincluded with the reactant charge. The reaction is driven to completionby distillation under reduced pressure (typically 2-50 mm Hg absolute at200°-250° C.) until the desired amount of water or methanol is obtained.The distillation under vacuum removes the final traces of water ormethanol, any excess glycol and also small amounts of other volatilematerials. The plasticizer is then cooled and is normally ready for use.As a practical matter, if the methyl esters of aliphatic acids areemployed, the aromatic acid will also be utilized as the methyl ester.

If an improvement in color is desired, the product may be bleached byany of the well known and accepted bleaching methods, e.g., usinghydrogen peroxide or hypochlorite. Alternatively, the copolyester can bedecolorized by filtering through a filter aid, charcoal or bleachingclay.

Whereas the reaction may be carried out without use of a catalyst, whereshorter reaction times are desired, a catalyst may be advantageous.Known catalysts, such as phosphoric acid, p-toluene sulfonic acid,stannous oxalate, alkyltin oxides, or the like can be utilized in smallamounts and facilitate the reaction. When the reaction is complete, thecatalyst may be deactivated or removed by filtering or otherconventional means. Catalysts are particularly advantageous for thetransesterification reactions.

Inert diluents such as benzene, toluene, xylene, and the like can beemployed for the reaction, however, they are not necessary. In fact, itis generally considered to be desirable to conduct the reaction withoutdiluents since the copolyester can be used directly as it is obtainedfrom the reactor.

The copolyester plasticizer compositions of the present invention areuseful plasticizers for PVC homopolymers and PVC copolymers wherein oneor more other ethylenically unsaturated monomers is copolymerized withvinyl chloride. Comonomers useful in the preparation of the polyvinylchloride copolymers include: vinyl bromide; vinyl acetate; vinylidenechloride; lower allyl esters; vinyl alkyl ethers; acrylonitrile andmethacrylonitrile; acrylic acid and methacrylic acid; acrylic andmethacrylic esters such as methyl acrylate, ethyl acrylate and methylmethacrylate; styrene; and the like. The copolyesters are particularlyuseful with copolymers of vinyl chloride with vinyl acetate, vinylchloride with vinyl butyrate, vinyl chloride with vinyl propionate,vinyl chloride with methyl methacrylate, vinyl chloride with vinylidenechloride and vinyl chloride with two or more comonomers, such asmixtures of vinylidene chloride and 2-ethylhexylacrylate, particularlywhen the copolymers contain 75 percent by weight or more bound vinylchloride.

The amount of copolyester used can be widely varied and will range fromabout 30 up to about 150 parts by weight per 100 parts by weight of thevinyl chloride homopolymer or copolymer. In a particularly usefulembodiment of the invention where the copolyester is utilized for theplasticization of PVC refrigerator gaskets, from about 60 to 110 partsby weight plasticizer per 100 parts resin is utilized. The copolyesterscan be utilized in combination with other plasticizers. When combinedwith other plasticizers, the total amount of plasticizer will generallyfall within the above-prescribed ranges.

The copolyesters of this invention are also compatible with other knowncompounding ingredients commonly employed in the formulation of PVC.Such ingredients include stabilizers to protect the resin from thedeleterious effects of oxidative, thermal and photochemical degradation,fillers, pigments, dyes, lubricants, and other processing aids. As isevident to those skilled in the art of compounding and formulating PVC,the type and amount of compounding ingredients used will be determinedby the physical properties desired.

In spite of the superior plasticization efficiency of the copolyestercompositions of this invention for PVC homopolymers and copolymers, theproducts have reduced affinity for polystyrene and ABS resins andtherefore exhibit little tendency to migrate into these resins when theycome into contact with PVC plasticized therewith. In one embodiment ofthe invention, copolyesters which have superior resistance to marring ofpolystyrene and ABS resins are obtained utilizing dimethylterephthalate. It is particularly advantageous if the acid component isa mixture of dimethyl terephthalate and mixed methyl esters of aliphaticdicarboxylic acids obtained as a co-product from the manufacture ofadipic acid.

The following examples illustrate the invention more fully. They arenot, however, intended as a limitation on the scope thereof. In theexamples all weights and percentages are on a weight basis unlessotherwise indicated.

EXAMPLE I

A typical copolyester plasticizer was prepared by reacting thefollowing:

    ______________________________________                                        Reactant        Equivalent Percent                                            ______________________________________                                        Azelaic Acid    24.8                                                          Adipic Acid     24.8                                                          Phthalic Anhydride                                                                            50.4                                                          Ethylene glycol*                                                                              35.0                                                          Neopentyl glycol                                                                              35.0                                                          2-Ethylhexanol* 30.0                                                          ______________________________________                                         *The charge contained 1.2 fold excesses of the volatile hydroxyl              components (ethylene glycol and 2ethylhexanol) to aid in driving the          reaction to completion.                                                  

The above ingredients were charged to a three-necked, round bottom flaskequipped with a suitable agitator, a thermometer, and a medium lengthVigreaux distillation column and condenser. The condenser was arrangedso that material could be distilled from the reaction at eitheratmospheric or reduced pressure. A small amount H₃ PO₂ (0.01 weightpercent) and dibutyltin diacetate (0.03 weight percent) were added tothe reactor and the reaction mixture heated to 225°-235° C. whileremoving water of reaction. The temperature was maintained until thereaction slowed, as evidenced by a marked reduction in the rate of waterevolution. At this point, a vacuum was applied. The pressure wasgradually reduced to a final pressure of about 2 mm Hg with thetemperature at 225°-250° C. so that controlled distillation of thevolatile components (water and excess alcohol) was achieved. Thereaction was followed by measuring the acid value (AV) of the reactionmixture and terminated when the AV was less than 0.5. The reactionmixture was then cooled to room temperature and filtered using adiatomaceous earth filter aid to remove catalyst and other impurities.The final copolyester product had an average molecular weight of 922, AVof 0.3, hydroxyl value (OHV) of 15.7 and kinematic viscosities at 100°F. and 210° C. of 1218 cSt and 105 cSt, respectively. The clear,essentially colorless liquid was useful as a plasticizer without furthermodification or processing and was readily incorporated into PVC resinhomopolymers and copolymers using conventional processing equipment toproduce clear pliable sheets.

A standard PVC resin formulation was prepared in accordance with thefollowing recipe:

    ______________________________________                                                               PHR                                                    ______________________________________                                        PVC resin (GEON 102)     100                                                  Barium-Cadmium Stabilizer (FERRO 1820)                                                                 2                                                    Phosphite Stabilizer (FERRO 904)                                                                       1                                                    Copolyester Plasticizer  67                                                   ______________________________________                                    

The ingredients were milled for about 10 minutes on a standard two-rollrubber mill (6×12 inch rolls heated to about 170° C. and set for a sheetthickness of about 0.25 inch). Sheets of uniform 20 mil thickness werethen prepared by pressing using a chrome-plated ASTM mold at about 177°C. for 6 minutes at 1500 psi. Test specimens were cut from the pressedsheet and physical properties determined using conventional testmethods. Properties of the plasticized resin were as follows:

    ______________________________________                                        Elongation (%)           290                                                  100% Modulus (psi)       1623                                                 Tensile Strength (psi)   3350                                                 Shore "A" Hardness       86/82                                                Roll Spew (5 hours at RT)                                                                              None                                                 Brittle Point (°C.)                                                                             -5                                                   Extraction (percent weight loss):                                             Soapy Water (90° C.; 24 hours)                                                                  4.4                                                  Oil (50° C.; 24 hours)                                                                          1.1                                                  Hexane (25° C.; 24 hours)                                                                       1.2                                                  ______________________________________                                    

The above data shows that excellent physical properties are obtained forthe PVC plasticized with the copolyester of the present invention.

EXAMPLE II

To demonstrate the ability to vary the composition, Example I wasrepeated using the following reactant charge:

    ______________________________________                                        Reactant        Equivalent Percent                                            ______________________________________                                        Azelaic Acid    24.8                                                          Adipic Acid     24.8                                                          Phthalic Anhydride                                                                            50.4                                                          Ethylene glycol 37.5                                                          Neopentyl glycol                                                                              37.5                                                          2-Ethylhexanol  25.0                                                          ______________________________________                                    

A slight excess of ethylene glycol and 2-ethylhexanol was employed. Theresulting copolyester composition had an average molecular weight of1850, an AV of 0.3, OHV of 17.3, 100° F. and 210° F. kinematicviscosities of 2005 cSt and 183 cSt, respectively. Plasticized PVCformulated in accordance with the recipe of Example I had the followingproperties:

    ______________________________________                                        Elongation (%)           280                                                  100% Modulus (psi)       1650                                                 Tensile Strength (psi)   3400                                                 Shore "A" Hardness       87/83                                                Roll Spew (5 hours at RT)                                                                              None                                                 Brittle Point (°C.)                                                                             -3                                                   Extraction (percent weight loss):                                             Soapy Water (90° C.: 24 hours)                                                                  3.0                                                  Oil (50° C.; 24 hours)                                                                          1.0                                                  Hexane (25° C.; 24 hours)                                                                       1.0                                                  ______________________________________                                    

EXAMPLE III

For comparative purposes, a copolyester derived solely from aliphaticdibasic acids and a mixture of neopentyl glycol and propylene glycol ofthe type typically utilized commercially for the formulation of PVCrefrigerator gaskets was prepared from the following reactants:

    ______________________________________                                        Reactant        Equivalent Percent                                            ______________________________________                                        Adipic Acid     45.5                                                          Azelaic Acid    45.0                                                          Mixed C.sub.8-20                                                                              9.0                                                           Monocarboxylic Acids                                                          Neopentyl glycol                                                                              50.0                                                          Propylene glycol                                                                              50.0                                                          ______________________________________                                    

The reaction was carried out following the procedure of Example I and aslight excess of propylene glycol was employed as an aid in driving theesterification reaction toward completion. The resulting copolyester hadan AV of 0.3, OHV of 20.0, and 100° F. and 210° F. kinematic viscositiesof 1637 cSt and 122 cSt, respectively.

EXAMPLE IV

PVC refrigerator gasket formulations were prepared using the copolyesterproduct of this invention prepared in Example I and the typical priorart copolyester product prepared in Example II. The resin formulationswere prepared in accordance with the following recipe:

    ______________________________________                                                              PHR                                                     ______________________________________                                        VYGEN 112 PVC           100.0                                                 Calcium Carbonate       50.0                                                  Epoxidized Soya         5.0                                                   Titanium Dioxide        1.5                                                   Stabilizer (Ba-Cd soaps and phosphite)/                                                               5.8                                                   Fungicide Package                                                             Plasticizer             95.0                                                  ______________________________________                                    

The ingredients were blended on a standard two-roll mill as described inExample I and physical properties of the plasticized resins determined.The properties of the vinyl formulation were as follows:

    ______________________________________                                                         Plasticizer  Plasticizer                                                      of Ex. I     of Ex. III                                      ______________________________________                                        Elongation (%)     330            370                                         100% Modulus (psi) 640            450                                         Tensile Strength (psi)                                                                           1875           1325                                        Roll Spew (5 hours at RT)                                                                        None           None                                        Brittle Point (°C.)                                                                       -7             -28                                         Extraction (percent weight loss):                                             Water (48 hours; 150° F.)                                                                 0.5            0.6                                         WESSON Oil (48 hours; RT)                                                                        0.6            2.5                                         JOY (48 hours; 150° F.)                                                                   1.5            0.9                                         ______________________________________                                    

It is apparent from the above data that physical properties obtained forthe resin formulation containing the plasticizer of Example I arecomparable to those obtained using the commercial plasticizer of ExampleIII. Furthermore, both formulations exhibited comparable resistance tomigration and resistance to marring of ABS and polystyrene resins.

Whereas the copolyester of Example I which used ethylene glycol with theneopentyl glycol and phthalic anhydride with the aliphatic acids and thecopolyester of Example III which contained no ethylene glycol andphthalic anhydride had comparable plasticization efficiency, resistanceto migration and resistance to marring, significant processingimprovements are obtained by the use of the plasticizers of thisinvention. To demonstrate these advantages, dry blend and fusioncharacteristics of the above formulations were determined using a torquerheometer (Brabender Plasticorder) in accordance with ASTM DesignationsD 2396-79 and D 2538-79, respectively. The powder mix (dry blending)evaluation was carried out at two different temperatures (100° C. and85° C.) for comparison purposes. Both evaluations were run using 300grams of the resin formulation using a sigma mixing head at 63 rpm. Dryblending results obtained for the resin formulations were as follows:

    ______________________________________                                                         Plasticizer                                                                             Plasticizer                                                         of Ex. I  of Ex. III                                         ______________________________________                                        Dry-Blending at 100° C.:                                               Time to Peak Torque (Minutes                                                                     1'30"       1'45"                                          and Seconds)                                                                  Peak Torque (Meter-Grams)                                                                        130         160                                            Dry-Blending at 85° C.:                                                Time to Peak Torque (Minutes                                                                     5'15"       8'30"                                          and Seconds)                                                                  Peak Torque (Meter-Grams)                                                                        100         140                                            ______________________________________                                    

It is apparent from the above data that the product formulated utilizingthe copolyester of Example I requires less time and lower torque (lesswork) to achieve dry blending. Higher throughputs are therefore possiblewith substantial energy savings using standard equipment and standardoperating conditions. Also, as a result of the improved mixing abilityit may be possible to accomplish dry-blending at lower operatingtemperatures.

Fusion characteristics for two resin formulations were determined using70 grams of dry-blended material run using a No. 6 roller head at 170°C. and 31.5 rpm. Fusion time (time to peak fusion minus time to initialfusion) for the formulation containing the copolyester of Example IIIwas 60 seconds whereas only 45 seconds were required to achieve fusionof the formulation plasticized with the copolyester of Example I. Thus,utilizing the copolyester products of this invention it is possible toincrease the extrusion throughput and/or reduce the residence time andtherefore heat history of the formulation during the extrusionoperation.

EXAMPLES V-IX

To demonstrate the versatility of the present invention and the abilityto vary the composition of the copolyester plasticizers, additionalreactions were carried out following the general procedure described forExample I. Types and amounts of reactants used and properties of theresulting copolyester products are reported in Table I. PVC formulationswere prepared as described in Example I. Where determined, physicalproperties obtained for the plasticized resins are set forth in TableII.

                  TABLE I                                                         ______________________________________                                                      EX.  EX.     EX.    EX.  EX.                                                  V    VI      VII    VIII IX                                     ______________________________________                                        Reactants:                                                                    Adipic Acid     58.1   45.3    45.6 24.8 32.3                                 Azelaic Acid    6.9    53.0    5.2  24.8 3.7                                  Phthalic Anhydride                                                                            --     49.4    49.2 50.4 34.9                                 Dimethyl        35.0   --      --   --   --                                   Terephthalate                                                                 Neopentyl Glycol                                                                              27.8   36.8    26.2 35.0 50.0                                 Ethylene Glycol 47.1   34.4    44.7 35.0 50.0                                 2-Ethylhexanol  --     28.8    --   --   --                                   2-Ethylhexanoic Acid                                                                          --     --      --   --   29.1                                 Isodecyl Alcohol                                                                              25.1   --      29.1 --   --                                   Isooctyl Alcohol                                                                              --     --      --   30.0 --                                   Properties:                                                                   Acid Value      0.2    0.8     0.4  0.5  0.8                                  Hydroxyl Value  9.0    13.8    0.9  11.4 17.3                                 100° F. Kinematic                                                                      905    1170    775  989  1168                                 Viscosity (cSt)                                                               ______________________________________                                    

                  TABLE II                                                        ______________________________________                                                       EX.   EX.     EX.     EX.                                                     V     VII     VIII    IX                                       ______________________________________                                        Elongation (%)   320     300     337   310                                    100% Modulus (psi)                                                                             1625    1650    1650  1625                                   Tensile Strenght (psi)                                                                         3400    3325    3475  3500                                   Shore "A"Hardness                                                                              85/80   83/79   83/79 82/77                                  Roll Spew (5 hours at RT)                                                                      None    None    None  None                                   Brittle Point (° C.)                                                                    -17     N.D.    -12   N.D.                                   Extraction (percent                                                           weight loss):                                                                 Soapy Water (90° C.; 24 hours)                                                          3.4     N.D.    5.3   N.D.                                   Oil (50° C.; 24 hours)                                                                  2.0     N.D.    1.7   N.D.                                   Hexane (25° C.; 24 hours)                                                               4.7     N.D.    2.3   N.D.                                   ______________________________________                                         N.D. = not determined                                                    

EXAMPLE X

To further demonstrate the preparation of copolyester compositionsderived from dimethyl terephthalate which exhibit superior resistance tomarring of polystyrene and ABS resins, the following were reacted:

    ______________________________________                                        Reactants          Equivalent Percent                                         ______________________________________                                        Methyl Esters of Mixed                                                                           48.7                                                       Dicarboxylic Acids.sup.1                                                      Dimethyl Terephthalate                                                                           26.2                                                       Mixed Monocarboxylic Acids.sup.2                                                                 25.1                                                       Neopentyl Glycol   37.1                                                       Ethylene Glycol.sup.3                                                                            62.9                                                       ______________________________________                                         .sup.1 A commercially available coproduct stream from the production of       adipic acid containing approximately 76% dimethyl ester of glutaric acid      and 24% dimethyl ester of adipic acid.                                        .sup.2 60% C.sub.8 and 40% C.sub.10 dicarboxylic acids.                       .sup.3 The charge included a 1.2 fold excess of hydroxyl component as         ethylene glycol to aid in driving the reaction to completion.            

The reactants were charged to the reactor and gradually heated to 223°C. 0.01 Weight percent 50% H₃ PO₂ and 0.01 weight percent tin catalystwere added when the reaction mixture became clear (approx. 80° C.).First traces of methanol began condensing at about 180° C. When the rateof methanol evolution slowed, a vacuum was applied and graduallyincreased up to a maximum of 1.2 torr to remove final traces ofmethanol. The resulting copolyester (837 grams) had an acid value of0.1, hydroxyl value of 16.4, and 100° F. kinematic viscosity of 1348centistokes. The product was clear at room temperature and essentiallycolorless and was an effective plasticizer for PVC.

EXAMPLES XI-XIII

Example X was repeated with the following reactants:

    ______________________________________                                                       Equivalent Percent                                             Reactants        EX. XI  EX. XII    EX. XIII                                  ______________________________________                                        Methyl Esters of Mixed                                                                         65.0    --         --                                        Dicarboxylic Acids                                                            Adipic Acid      --      58.1       65.0                                      Azelaic Acid     --      6.9        --                                        Dimethyl Terephthalate                                                                         35.0    35.0       35.0                                      Neopentyl Glycol 27.8    27.8       27.8                                      Ethylene Glycol.sup.1                                                                          47.1    47.1       47.1                                      Isodecyl Alcohol.sup.1                                                                         25.1    25.1       25.1                                      ______________________________________                                         .sup.1 The charge included (1.2 fold excesses of the volatile hydroxyl        components (ethylene glycol and isodecyl alcohol) to aid in driving the       reaction to completion.                                                  

The yield (grams), acid value, hydroxyl value, and 100° F. kinematicviscosity (centistokes) for each of the resulting products were asfollows:

    ______________________________________                                                  EX. XI    EX. XII  EX. XIII                                         ______________________________________                                        Yield       1097        993      1009                                         Acid Value  0.1         0.2      0.2                                          Hydroxyl Value                                                                            7.1         9.0      8.7                                          Viscosity   1280        905      975                                          ______________________________________                                    

EXAMPLE XIV

Whereas all of the products of this invention prepared in the foregoingexamples are effective plasticizers for PVC and give acceptable resultsin the so-called "sandwich test" for marring (see U.S. Pat. No.3,972,962, Example VIII), the products of Examples V and X-XIII preparedusing dimethyl terephthalate in accordance with the preferred embodimentof this invention quite unexpectedly have significantly reduced affinityfor polystyrene and ABS resins which is not evident from the "sandwichtest." To demonstrate the markedly reduced affinity of the preferredcopolyester compositions, a "dip test" was conducted using thecopolyesters prepared in accordance with the foregoing examples. For thetest, 100 ml beakers were filled with approximately 40 mls copolyesterplasticizer. A single test specimen (1"×3") cut from either 100 milthick compression molded commercially available unplasticizedpolystyrene (Mobil MX-7100A) or ABS was then placed in each beaker.Surfaces of the test strips were cleaned by wiping with isopropylalcohol and a soft tissue prior to testing. The beakers containing thetest specimens were then placed in an air-circulating oven at 150° F.for 16 hours. At the conclusion of the test period, the test strips werewiped with a soft tissue, visually inspected, and rated for mar. Anysurface tackiness was also noted. Mar ratings range from 0 (no marringor dulling of surface) to 4 (severe marring of surface accompanied bytackiness). Results obtained were as follows:

    ______________________________________                                                       Mar Rating                                                     Copolyester of:  Polystyrene                                                                             ABS                                                ______________________________________                                        EX. I            2         3                                                  EX. II           2         3                                                  EX. V            0         0                                                  EX. VI           2         3                                                  EX. VII          2         3                                                  EX. VIII         2         3                                                  EX. IX           2         3                                                  EX. X            1         1                                                  EX. XI           0         0                                                  EX. XII          0         0                                                  EX. XIII         0         0                                                  ______________________________________                                    

It is apparent from the above data that the copolyesters prepared usingthe dimethyl terephthalate have significantly reduced affinity forpolystyrene and ABS resins than the copolyesters prepared using phthalicanhydride. This reduced affinity for polystyrene and ABS provides anextra margin of safety in constructions, such as for refrigeratorgaskets, where plasticized PVC comes into contact with unplasticizedpolystyrene or ABS resins. This feature coupled with the improvedprocessability and reduced cost of the copolyesters of the presentinvention makes these products particularly useful plasticizers for PVC.

We claim:
 1. A polymer composition comprising a polyvinyl chloridehomopolymer or polyvinyl chloride copolymer and 30 to 150 parts byweight, per 100 parts resin, of an improved copolyester plasticizerhaving an average molecular weight of 500 to 2000 and 100° F. kinematicviscosity of 600 to 2000 centistokes obtained by the reaction of (a) amixture of a benzene dicarboxylic acid, anhydride or methyl esterthereof and an aliphatic saturated dicarboxylic acid having from 5 to 12carbon atoms or methyl ester thereof, said benzene dicarboxylic acid,anhydride or methyl ester being present in an amount from 40 to 60equivalent percent, based on the total acid equivalents, (b) a mixtureof neopentyl glycol and ethylene glycol, said neopental glycol beingpresent in an amount from 30 to 60 equivalent percent, based on thetotal alcohol equivalents, and said ethylene glycol being present in anamount from about 30 to 60 equivalent percent, based on the totalalcohol equivalents, and (c) an aliphatic saturated monofunctionalalcohol having from 6 to 13 carbon atoms or an aliphatic saturatedmonocarboxylic acid having from 6 to 13 carbon atoms or methyl esterthereof, said aliphatic saturated monofunctional alcohol or aliphaticsaturated monocarboxylic acid being present in ann amount from 8 to 30equivalent percent, based on the total equivalents of alcohol or acid.2. The polymer composition of claim 1 wherein the copolyesterplasticizer has an acid value less than 3 and hydroxyl value less than25.
 3. The polymer composition of claim 1 wherein (c) is an aliphaticsaturated monofunctional alcohol having from 8 to 10 carbon atoms. 4.The polymer composition of claim 3 wherein the aliphatic saturatedmonofunctional alcohol is selected from the group consisting of2-ethylhexanol, isooctyl alcohol or isodecyl alcohol.
 5. The polymercomposition of claim 3 wherein (a) is a mixture of phthalic anhydrideand an aliphatic saturated dicarboxylic acid having from 5 to 9 carbonatoms or a mixture of C₅₋₉ aliphatic saturated dicarboxylic acids. 6.The polymer composition of claim 3 wherein (a) is a mixture of dimethylterephthalate and an aliphatic saturated dicarboxylic acid having from 5to 9 carbon atoms or a mixture of C₅₋₉ aliphatic saturated dicarboxylicacids.
 7. The polymer composition of claim 6 wherein the aliphaticsaturated dicarboxylic acid is adipic acid, azeleic acid or a mixture ofadipic and azeleic acids.
 8. The polymer composition of claim 3 wherein(a) is a mixture of dimethyl terephthalate and a methyl ester of analiphatic acid saturated dicarboxylic acid having from 5 to 9 carbonatoms or a mixture of methyl esters of predominantly C₅₋₉ aliphaticsaturated dicarboxylic acids.
 9. The polymer composition of claim 8wherein the methyl esters of aliphatic saturated dicarboxylic acids aremixture obtained as a co-product stream from the production of adipicacid and comprised essentially of dimethyl gluterate and dimethyladipate acid present in a ratio from 4:1 to 1:1.
 10. The polymercomposition of claim 8 wherein the methyl esters of the aliphaticsaturated dicarboxyli acids are the methyl ester of adipic acid, azeleicacid or mixture of adipic and azeleic acids.
 11. The polymer compositionof claim 1 wherein (c) is an aliphatic saturated monocarboxylic acidhaving from 8 to 10 carbon atoms.
 12. The polymer composition of claim11 wheren (a) is a mixture of phthalic anhydride and an aliphaticsaturated dicarboxylic acid having from 5 to 9 carbon atoms or a mixtureof C₅₋₉ aliphatic saturated dicarboxylic acids.
 13. The polymercomposition of claim 11 wherein (a) is a mixture of dimethylterephthalate and an aliphatic saturated dicarboxylic acid having from 5to 9 carbon atoms or a mixture of C₅₋₉ aliphatic saturated dicarboxylicacids.
 14. The polymer composition of claim 13 wherein the aliphaticsaturated dicarboxylic acid is adipic acid, azeleic acid or a mixture ofadipic and azeleic acids.
 15. The polymer composition of claim 11wherein (a) is a mixture of dimethyl terephthalate and a methyl ester ofan aliphatic acid saturated dicarboxylic acid having from 5 to 9 carbonatoms or a mixture of methyl esters of predominantly C₅₋₉ aliphaticsaturated dicarboxylic acids.
 16. The polymer composition of claim 15wherein the methyl esters of aliphatic saturated dicarboxylic acids aremixture obtained as a co-product stream from the production of adipicacid and comprised essentially of dimethyl glutarate and dimethyladipate present in a ratio from 4:1 to 1:1.
 17. The polymer compositionof claim 15 wherein the methyl esters of the aliphatic saturateddicarboxylic acids are the methyl ester of adipic acid, azeleic acid ormixture of adipic and azeleic acids.